In the Social Structure class we are working through the classic studies of social mobility (for SOC nerds that is Blau and Duncan, as modified by Jencks). They look at which factors in your background help predict your likely socioeconomic status (SES).
The basic finding is roughly this:
The class of your family, plus the way that class shapes your schooling, predicts a fifth to a quarter of your ultimate SES.
Your own education predicts another fifth to a quarter.
The other 50 or 60% is due to other factors - including your own effort in getting, keeping, and improving in a job.
As we talked about it, it seemed to me that this is an ethically satisfying distribution. As a parent, I am glad that my efforts to help my children be cultivated and successful do matter. As a teacher I am glad that education adds a sizable hunks to my students' ultimate success. And as a citizen I am glad that there is such ample scope for personal effort to make the biggest difference in one's achievement.